A zero discharge method for electroplating tin-containing wastewater

Abstract

This invention provides a method for zero discharge of tin-containing wastewater from electroplating. (1) The collected wastewater is introduced into a first reaction tank for acidification and demulsification; (2) The acidified and demulsified wastewater is introduced into a second reaction tank for alkalization and precipitation. Then, the temperature of the wastewater is raised to 50-70°C, and hydrogen peroxide is added and stirred for 30-40 minutes for oxidation reaction; (3) The alkalized wastewater is then subjected to preliminary filtration to remove precipitate, ion exchange resin treatment, and fine filtration, and finally, the effluent meets the standards. This method for zero discharge of tin-containing wastewater from electroplating has the advantages of high efficiency, economy, and environmental protection. It can effectively solve the problem of tin-containing wastewater treatment generated during electroplating, realize the resource utilization and zero discharge of wastewater, and is of great significance for the sustainable development and environmental protection of the electroplating industry.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for zero discharge of tin-containing wastewater from electroplating. Background Technology

[0002] Electroplating wastewater refers to various wastewater generated during the electroplating production process, including pickling wastewater, rinsing wastewater, passivation wastewater, wastewater from washing floors and plates, and wastewater generated due to leaks or spills caused by poor operation or management. The quality and quantity of electroplating wastewater are closely related to the electroplating process conditions, production load, operation management, and water usage. A common characteristic of electroplating wastewater is its complex composition, which is difficult to control. It contains highly toxic heavy metal ions such as chromium, cadmium, nickel, copper, zinc, gold, and silver, as well as cyanides, which cannot be degraded by simple biochemical methods. Some pollutants are even highly toxic substances that are carcinogenic and mutagenic. Therefore, electroplating wastewater treatment has always been a recognized high-difficulty problem in the industry.

[0003] Tin-containing wastewater exhibits certain unique characteristics in electroplating wastewater. Tin is a common electroplating metal, but the presence of tin ions, along with other potentially heavy metal ions and organic matter, in tin-containing wastewater during the electroplating process makes its treatment particularly complex. Traditional wastewater treatment methods, such as chemical precipitation and biochemical methods, while capable of removing pollutants to some extent, often suffer from low treatment efficiency and unstable effluent quality, making it difficult to meet current stringent environmental protection requirements.

[0004] With increasing environmental awareness and increasingly stringent environmental regulations, zero-discharge technology for electroplating wastewater has gradually become an important development direction for the electroplating industry. Zero-discharge technology aims to treat electroplating wastewater and achieve complete reuse, without discharging any wastewater into the environment. This not only reduces environmental pollution but also enables the recycling of water resources, lowering production costs for enterprises.

[0005] In the development of zero-discharge technology for electroplating wastewater, various advanced technologies have been continuously introduced and applied. For example, membrane separation technology, evaporation crystallization technology, and adsorption technology have all played important roles in electroplating wastewater treatment. These technologies not only improve the efficiency of wastewater treatment but also significantly enhance the quality of effluent, providing strong support for achieving zero discharge of electroplating wastewater.

[0006] Although some progress has been made in zero-discharge technology for electroplating wastewater, some shortcomings still exist. For example, existing treatment technologies often suffer from high treatment costs, complex operation, and difficult equipment maintenance. Furthermore, because electroplating wastewater contains a wide variety of pollutants, different types of wastewater require different treatment methods, which also increases the difficulty and cost of treatment.

[0007] Therefore, developing an efficient, economical, and easy-to-operate method for zero discharge of tin-containing electroplating wastewater is of great significance. Against this background, this invention provides a method for zero discharge of tin-containing electroplating wastewater. Summary of the Invention

[0008] The purpose of this invention is to provide a method for zero discharge of tin-containing wastewater from electroplating, which is efficient, economical, easy to operate, and effectively achieves the treatment of tin-containing wastewater from electroplating.

[0009] This invention provides a method for zero discharge of tin-containing wastewater from electroplating, comprising the following steps:

[0010] (1) The collected wastewater is introduced into the first reaction tank for acidification and demulsification;

[0011] (2) The acidified and demulsified wastewater is introduced into the second reaction tank for alkalization and precipitation. Then the temperature of the wastewater is raised to 50-70℃, hydrogen peroxide is added and stirred for 30-40 min for oxidation reaction.

[0012] (3) Subsequently, the alkalized wastewater is subjected to preliminary filtration to remove sediment, ion exchange resin treatment and fine filtration steps in sequence, and finally meets the discharge standards.

[0013] Furthermore, the acidification step in step (1) includes adding sulfuric acid solution to the first reaction tank to adjust the pH of the wastewater in the first reaction tank to 2-4.

[0014] Further, in step (2), the alkalization step involves adding an 8-10% sodium hydroxide aqueous solution to the second reaction tank to adjust the pH of the wastewater to 4-5.

[0015] Furthermore, the hydrogen peroxide has a mass concentration of 1-2%, and the amount of hydrogen peroxide added is 8-12% of the wastewater volume.

[0016] Furthermore, the ion exchange resin is AMBERLITE IRA-400 anion exchange resin.

[0017] Furthermore, the ratio of the filter material to the wastewater in the fine filtration is (0.9-1.1) g / L, and the adsorption treatment time of the fine filtration is 6-8 h, with shaking for 6-10 min every 1 h.

[0018] Furthermore, the preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve, calcining it for the first time and then naturally cooling it to room temperature, soaking it in NaCl solution for 10-14 hours, shaking it for 1-2 minutes every 3 hours during the soaking process, filtering it, washing it with water, and drying it to obtain pre-modified zeolite; adding the pre-modified zeolite to KMnO4 solution and adding MnSO4 solution, placing it in a constant temperature shaker at 30-40℃ for gelation for 3-4 hours, aging it for 4-6 hours, centrifuging it, washing it, calcining it for the second time, and then grinding it to obtain the final product.

[0019] Furthermore, the first calcination temperature is 500-600℃ and the calcination time is 30-40 min; the second calcination temperature is 300-400℃ and the calcination time is 100-140 min.

[0020] Further, the concentration of the NaCl solution is 0.8-1.2 mol / L, the concentration of the KMnO4 solution is 0.03-0.04 mol / L, and the concentration of the MnSO4 solution is 0.04-0.05 mol / L.

[0021] Furthermore, the ratio of the amount of the pre-modified zeolite, KMnO4 solution and MnSO4 solution is (1-2)g:(300-360)mL:(360-400)mL.

[0022] The beneficial effects of this invention are as follows:

[0023] In this invention, under acidic conditions, emulsions and some organic matter in wastewater will undergo demulsification and decomposition, which helps in the formation of precipitates and the removal of metal ions in subsequent treatment.

[0024] In this invention, the acidified and demulsified wastewater is introduced into a second reaction tank, and sodium hydroxide solution is added. Under alkaline conditions, the tin ions (Sn) in the wastewater... 2+ It will react with hydroxide ions (OH-) - The organic matter combines with the tin hydroxide (Sn(OH)2) precipitate to form tin hydroxide. At the same time, raising the wastewater temperature to 60°C and adding hydrogen peroxide can promote the oxidation reaction, further decompose the organic matter, and accelerate the precipitation process.

[0025] This invention removes large particulate precipitates and suspended solids from wastewater through preliminary filtration and utilizes the adsorption capacity of modified zeolite. The modified zeolite is prepared through calcination, soaking, and gelation, and its surface has abundant active sites and a porous structure, enabling it to efficiently adsorb metal ions (such as tin, nickel, copper, aluminum, zinc, etc.) and organic matter from wastewater.

[0026] In this invention, the zeolite is first pre-modified. The first calcination removes organic impurities and moisture from the zeolite, enhancing its structural stability and exposing more active sites on the zeolite surface. Subsequent deep modification involves adding the pre-modified zeolite to a solution containing KMnO4 and MnSO4. KMnO4, as a strong oxidizing agent, oxidizes the functional groups on the zeolite surface, increasing its surface electronegativity and thus enhancing its adsorption capacity for metal ions. Simultaneously, Mn... 2+ Ions can bind to active sites on the zeolite surface, forming new adsorption centers. Gelation also facilitates the uniform distribution and deep penetration of KMnO4 and MnSO4 on the zeolite surface, while aging further stabilizes the zeolite structure and enhances its adsorption performance. Furthermore, the second calcination can immobilize KMnO4 and MnSO4. 2+ The modification effect on the zeolite surface removes excess organic impurities and moisture, allowing the zeolite to achieve optimal adsorption performance.

[0027] The active sites and new adsorption centers on the modified wastewater surface of this invention can undergo ion exchange with metal ions in the wastewater, fixing the metal ions inside the zeolite and thus reducing the concentration of metal ions in the wastewater. Furthermore, the porous structure and large specific surface area of ​​the zeolite enable it to adsorb metal ions and organic matter in the wastewater, fixing them to the zeolite surface and interior through physical action.

[0028] The treatment method in this invention can effectively remove tin and other metal ions from wastewater, while organic matter is also decomposed or adsorbed and removed. Ultimately, the wastewater after fine filtration meets discharge standards and can even be directly reused in production processes, such as equipment cleaning, achieving true zero discharge. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] This embodiment provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0032] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0033] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0034] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0035] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 550℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 3.5 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 350℃ and the calcination time is 120 min.

[0036] Example 2

[0037] This embodiment provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0038] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0039] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. An 8% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4 for alkalization and precipitation. Then the temperature of the wastewater is raised to 50°C, and 1% hydrogen peroxide is added and stirred for 30 min for oxidation reaction. The amount of hydrogen peroxide added is 8% of the volume of the wastewater.

[0040] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of filter material to wastewater in fine filtration was 0.9 g / L, the adsorption treatment time of fine filtration was 6 h, and the water was shaken for 6 min every 1 h. Finally, the effluent met the standards.

[0041] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 500℃ and the calcination time is 30 min; soaking it in a 0.8 mol / L NaCl solution for 10 h, shaking it for 1 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.03 mol / L KMnO4 solution and a 0.04 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1 g: 300 mL: 360 mL; gelling it in a 30℃ constant temperature shaker for 3 h, aging it for 4 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 300℃ and the calcination time is 100 min.

[0042] Example 3

[0043] This embodiment provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0044] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 4 for acidification and demulsification.

[0045] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. An 8-10% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 70°C, and 2% hydrogen peroxide is added and stirred for 40 min for oxidation reaction. The amount of hydrogen peroxide added is 12% of the volume of the wastewater.

[0046] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of filter material to wastewater in fine filtration was 1.1 g / L, the adsorption treatment time of fine filtration was 8 h, and the water was shaken for 10 min every 1 h. Finally, the effluent met the standards.

[0047] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 600℃ and the calcination time is 40 min; soaking it in a 1.2 mol / L NaCl solution for 14 h, shaking it for 2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.04 mol / L KMnO4 solution and a 0.05 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 2 g: 360 mL: 400 mL; gelling it in a 40℃ constant temperature shaker for 4 h, aging it for 6 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 400℃ and the calcination time is 140 min.

[0048] Example 4

[0049] This embodiment provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0050] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 2 for acidification and demulsification.

[0051] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 10% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4 for alkalization and precipitation. Then the temperature of the wastewater is raised to 70°C, and 1% hydrogen peroxide is added and stirred for 40 min for oxidation reaction. The amount of hydrogen peroxide added is 8% of the volume of the wastewater.

[0052] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of filter material to wastewater in fine filtration was 0.9 g / L, the adsorption treatment time of fine filtration was 8 h, and the water was shaken for 6 min every 1 h. Finally, the effluent met the standards.

[0053] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 500℃ and the calcination time is 40 min; soaking it in a 0.8 mol / L NaCl solution for 14 h, shaking it for 1 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.04 mol / L KMnO4 solution and a 0.04 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 2 g: 300 mL: 400 mL; gelling it in a 30℃ constant temperature shaker for 4 h, aging it for 4 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 400℃ and the calcination time is 100 min.

[0054] Comparative Example 1

[0055] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0056] (1) The collected wastewater is introduced into the reaction tank. A 9% sodium hydroxide aqueous solution is added to the reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0057] (2) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of filter material to wastewater in fine filtration was 1 g / L, the adsorption treatment time of fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0058] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 550℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 3.5 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 350℃ and the calcination time is 120 min.

[0059] Comparative Example 2

[0060] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0061] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0062] (2) The acidified and demulsified wastewater is introduced into the second reaction tank, and a 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation.

[0063] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0064] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 550℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 3.5 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 350℃ and the calcination time is 120 min.

[0065] Comparative Example 3

[0066] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0067] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0068] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0069] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0070] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve, adding it to a KMnO4 solution with a concentration of 0.035 mol / L, and adding a MnSO4 solution with a concentration of 0.045 mol / L. The ratio of the amount of pre-modified zeolite, KMnO4 solution and MnSO4 solution is 1.5 g: 330 mL: 380 mL. The mixture is placed in a constant temperature shaker at 35°C for 3.5 h, aged for 5 h, centrifuged and washed, and then calcined a second time and ground to obtain the final product. The second calcination temperature is 350°C and the calcination time is 120 min.

[0071] Comparative Example 4

[0072] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0073] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0074] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0075] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0076] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve, calcining it for the first time and then naturally cooling it to room temperature. The first calcination temperature is 550℃ and the calcination time is 35min. Soaking it in a 1mol / L NaCl solution for 12h, shaking it for 1-2min every 3h during the soaking process, filtering it, washing it with water and drying it are then obtained.

[0077] Comparative Example 5

[0078] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0079] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0080] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0081] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0082] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 550℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 2 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 350℃ and the calcination time is 120 min.

[0083] Comparative Example 6

[0084] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0085] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0086] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0087] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0088] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 550℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 5 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 350℃ and the calcination time is 120 min.

[0089] Comparative Example 7

[0090] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0091] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0092] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0093] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0094] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 400℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 3.5 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 350℃ and the calcination time is 120 min.

[0095] Comparative Example 8

[0096] This comparative example provides a method for zero discharge of tin-containing electroplating wastewater, the steps of which include:

[0097] (1) The collected wastewater is introduced into the first reaction tank, sulfuric acid solution is added, and the pH of the wastewater in the first reaction tank is adjusted to 3 for acidification and demulsification.

[0098] (2) The acidified and demulsified wastewater is introduced into the second reaction tank. A 9% sodium hydroxide aqueous solution is added to the second reaction tank to adjust the pH of the wastewater to 4.5 for alkalization and precipitation. Then the temperature of the wastewater is raised to 60°C, and 1.5% hydrogen peroxide is added and stirred for 35 min for oxidation reaction. The amount of hydrogen peroxide added is 10% of the volume of the wastewater.

[0099] (3) Subsequently, the alkalized wastewater was subjected to preliminary filtration to remove sediment, AMBERLITE IRA-400 anion exchange resin treatment and fine filtration. The ratio of the filter material to the wastewater in the fine filtration was 1 g / L, the adsorption treatment time of the fine filtration was 7 h, and the water was shaken for 8 min every 1 h. Finally, the effluent met the standards.

[0100] The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve; calcining it for the first time and then naturally cooling it to room temperature; the first calcination temperature is 550℃ and the calcination time is 35 min; soaking it in a 1 mol / L NaCl solution for 12 h, shaking it for 1-2 min every 3 h during the soaking process; filtering, washing with water, and drying to obtain pre-modified zeolite; adding the pre-modified zeolite to a 0.035 mol / L KMnO4 solution and a 0.045 mol / L MnSO4 solution, with the ratio of pre-modified zeolite, KMnO4 solution, and MnSO4 solution being 1.5 g: 330 mL: 380 mL; gelling it in a 35℃ constant temperature shaker for 3.5 h, aging it for 5 h, centrifuging it, washing it, and then calcining it a second time and grinding it to obtain the final product; the second calcination temperature is 500℃ and the calcination time is 120 min.

[0101] Wastewater was treated using the zero-treatment method for tin-containing electroplating wastewater provided in Examples 1-4 and Comparative Examples 1-6. The wastewater quality of a certain factory's electroplating wastewater was as follows: tin concentration 166 mg / L, nickel concentration 96 mg / L, copper concentration 106 mg / L, aluminum concentration 102 mg / L, and zinc concentration 77 mg / L.

[0102] The test results after wastewater treatment are shown in the table below:

[0103] Example 1 0.10 0.08 0.21 0.14 0.02 Example 2 0.11 0.09 0.22 0.15 0.02 Example 3 0.13 0.10 0.21 0.15 0.03 Example 4 0.14 0.12 0.25 0.17 0.05 Comparative Example 1 17.35 3.52 7.85 4.40 2.25 Comparative Example 2 12.41 2.11 5.41 3.81 1.04 Comparative Example 3 11.72 1.76 4.72 3.54 0.92 Comparative Example 4 6.52 1.42 4.14 3.17 0.64 Comparative Example 5 3.96 1.15 3.22 2.26 0.42 Comparative Example 6 5.71 1.37 3.87 2.74 0.55 Comparative Example 7 2.84 1.06 2.86 1.77 0.36 Comparative Example 8 3.42 1.15 3.02 2.03 0.49

[0104] Examples 1-4 above show that the tin-containing electroplating wastewater treated by the method of the present invention is all below the national emission standards.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for zero discharge of electroplating tin containing wastewater, characterized by the steps of include: (1) The collected wastewater is introduced into the first reaction tank for acidification and demulsification; the acidification step includes adding sulfuric acid solution to the first reaction tank to adjust the pH of the wastewater in the first reaction tank to 2-4; (2) The acidified and demulsified wastewater is introduced into the second reaction tank for alkalization and precipitation. After alkalization and precipitation, the wastewater temperature is raised to 50-70℃ without filtration, and hydrogen peroxide is added and stirred for 30-40 minutes for oxidation reaction. The alkalization step is to add sodium hydroxide aqueous solution with a mass concentration of 8-10% to the second reaction tank to adjust the pH value of the wastewater to 4-5. (3) Subsequently, the alkalized wastewater is subjected to preliminary filtration to remove sediment, ion exchange resin treatment and fine filtration in sequence, and finally meets the discharge standards; The ratio of filter material to wastewater in the fine filtration process is (0.9-1.1) g / L, and the adsorption treatment time for the fine filtration is 6-8 h, with shaking for 6-10 min every 1 h. The preparation method of the filter material for fine filtration includes: crushing natural zeolite and passing it through a 200-mesh sieve, calcining it for the first time and then naturally cooling it to room temperature, soaking it in NaCl solution for 10-14 hours, shaking it for 1-2 minutes every 3 hours during the soaking process, filtering it, washing it with water, and drying it to obtain pre-modified zeolite; adding the pre-modified zeolite to KMnO4 solution and adding MnSO4 solution, placing it in a constant temperature shaker at 30-40℃ for gelation for 3-4 hours, aging it for 4-6 hours, centrifuging it, washing it, calcining it for the second time, and then grinding it to obtain the final product.

2. The electroplating tin-containing wastewater zero discharge method according to claim 1, characterized in that, The hydrogen peroxide has a mass concentration of 1-2%, and the amount of hydrogen peroxide added is 8-12% of the wastewater volume.

3. The method for zero discharge of tin-containing electroplating wastewater according to claim 1, characterized in that, The ion exchange resin is AMBERLITE IRA-400 anion exchange resin.

4. The method for zero discharge of tin-containing electroplating wastewater according to claim 1, characterized in that, The first calcination temperature is 500-600℃ and the calcination time is 30-40 min; the second calcination temperature is 300-400℃ and the calcination time is 100-140 min.

5. The method for zero discharge of tin-containing electroplating wastewater according to claim 1, characterized in that, The concentration of the NaCl solution is 0.8-1.2 mol / L, the concentration of the KMnO4 solution is 0.03-0.04 mol / L, and the concentration of the MnSO4 solution is 0.04-0.05 mol / L.

6. The method for zero discharge of tin-containing electroplating wastewater according to claim 1, characterized in that, The ratio of the amount of the pre-modified zeolite, KMnO4 solution and MnSO4 solution is (1-2) g: (300-360) mL: (360-400) mL.